Debt - $105 Million Secured Mortgage Notes Assumed (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Nov. 30, 2011 Acres	Dec. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]
Number of acres acquired		62,344		17,094,000
Carrying value of debt		$ 751,555,000		$ 1,574,224,000
Secured Mortgage Notes Assumed with Timberland Acquisition [Member]
Debt Instrument [Line Items]
Noncash or part noncash acquisition, debt assumed, date	November 2011
Number of acres acquired	250,000
Debt instrument, collateral	approximately 250,000 acres of timberlands
Noncash or part noncash acquisition, debt assumed	105,000,000
Fixed interest rate	4.35%	4.35%	[1]
Debt instrument term	7 years
Maturity date description	August 2017
Repayments of secured debt	21,000,000	10,500,000		10,500,000
Carrying value of debt		53,801,000	[1]	65,165,000	[1]
Outstanding principal		$ 52,500,000

[1] The mortgage notes due in 2017 were recorded at a premium of $1.3 million and $2.2 million as of December 31, 2014 and 2013, respectively. Upon maturity the liability will be $53 million.